Monitoring and blending of liquid fuel

ABSTRACT

Liquid fuels have their knock characteristics monitored by knock test engine operating alternately on the fuel to be tested and on a reference fuel. The difference in knock intensities can be used to control the in-line blending of the test fuel. Test engine has carburetor with fuel-level-determining device to which stream of test fuel is continuously fed faster than required by engine, excess fuel is diverted away from engine by overflow or suction take-off. Fuels can be cooled on way to engine. Compression ratio of knock test engine and/or signal indicator can have automatic adjustment when engine operates on reference fuel so as not to require attention of an operator.

United States Patent 1 Jones et al.

MONITORING AND BLENDING LIQUID FUEL Inventors: John T. Jones; William C. Ludt;

Hudson W. Kellogg, all of Dobbs Ferry, N.Y.

Assignee: Ethyl Corporation, Richmond, Va.

Filed: Sept. 5, 1972 Appl. No.: 286,230

Related US. Application Data Continuation-in-part of Ser. No. 886,458, Dec. 19, 1969, Pat. No. 3,690,851, and a continuation-in-part of Ser. No. 377,192, June 23, 1964, said Ser. No. 886,458, Division ofSer.No.6l7,754,Jan24, 1967, Pat. No. 3,485,598, which is a continuation-in-part of said Ser. No. 377,192, and Ser. No. 299,583, Aug. 2, 1963, abandoned, and Ser. No. 205,015, June 25, 1962, Pat. No. 3,383,904, said Ser. No.

[ 1 Oct. 21, 1975 OTHER PUBLICATIONS ASTM. Manual for Rating Motor Fuels by Motor & Research Methods 4th Edition, 1960 pp. 48 & 94.

Primary Examiner-James J. Gill [57] ABSTRACT Liquid fuels have their knock characteristics monitored by, knock test engine operating alternately on the fuel to be tested and on a reference fuel. The difference in knock intensities can be used to control the in-line blending of the test fuel. Test engine has carburetor with fuel-level-determining device to which stream of test fuel is continuously fed faster than required by engine, excess fuel is diverted away from engine by overflow or suction take-off. Fuels can be cooled on way to engine. Compression ratio of knock test engine and/or signal indicator can have automatic adjustment when engine operates on reference fuel so as not to require attention of an operator.

7 Claims, 15 Drawing Figures 1 ll 4 i sbdewme gg I I increase Decrease fimatzmz Pulse:- Pubser M gseguencel I I 1 l 15 l. z AlKy llfad Adddvue 31,

m %I 35! C'onb'ol Mzzve 52.

a 1 I R aJneter' Base Staci 52 40 Gmane Fm? 568mm J Gasoline U.S. Patent 'Oct.21, 1975 Sheet30f 12 3,913,380

N ASE QM QM Mm I l l l I l US. Patent Oct. 21, 1975 Sheet4of 12 3,913,380

b6 SE 28 \SALDW muioa 20mm US. Patent Oct. 21, 1975 Sheet5of 12 3,913,380

Ew/z/Dei'mz/ up Amplzfer with; I Rectifier U.S. Patent Oct. 21, 1975 Sheet6of 12 3,913,380

an I I man Sheet7 of 12 3,913,380

U.S. Patent Oct. 21, 1975 Sheet 8 of 12 U.S. Patent Oct. 21, 1975 bh /NMIG U.-S. Patent Oct. 21, 1975 Sheet 9 of 12 QWSQLQQ H 3 QENN LQ QQL QR mmGPBMQ QR Sheet 10 of 12 3,913,380

US. Patent Ot.-21, 1975 U.S. Patent Oct. 21, 1975 Sheet11of12 3,913,380

ntro/w) no BALANCING AIR SUPPLY SEQUENC E12 Q COMP 59 SHAFT OFASTM ENGINE 536 L MULTIPLE TURN SET PQ/Nr suns WIRE 9 06 J I I 5/20 502 MAGNETIC I I CLUTCH REDUCER MONITORING AND BLENDING F LIQUID FUEL The present application is a continuation-in-part of application Ser. No. 886,458 filed Dec. 19, 1969 (U.S. Pat. No. 3,690,851 granted Sept. 12, 1972) and Ser. No. 377,192 filed June 23, 1964. Application Ser. No. 886,458 is a division of application Ser. No. 617,754 filed Jan. 24, 1967, now U.S. Pat. No. 3,485,598 granted Dec. 23, 1969, which in turn is a continuationin-part of said Ser. No. 377,192 and of applications Ser. No. 299,583 filed Aug. 2, 1963 (now abandoned); and Ser. No. 205,015 filed June 25, 1962, now U.S. Pat. No. 3,383,904 granted May 21, 1968. Application Ser. No. 377,192 is also in part a continuation of said applications Ser. No. 299,583 and Ser. No. 205,015.

The present invention relates to the measurement and adjustment of antiknock ratings of fuels such as gasoline.

Among the objects of the present invention is the provision of novel methods and apparatus for monitoring the knock characteristics of the above type fuels.

The foregoing as well as additional objects of the present invention will be recognized from the following description of several of its embodiments, reference being made to the accompanying drawings wherein:

FIG. 1 is a schematic representation of an antiknock rating apparatus according to the present invention;

FIG. 2 is a generally diagrammatic view of the mechanical elements suitable for use in the apparatus of FIG. 1, showing a test engine and some of its related structures;

FIG. 3 is a partially schematic more detailed illustration of one form of an assembly of components that cooperate as in FIG. 1, to form an automatic rating apparatus representative of the present invention;

FIG. 4 is a circuit diagram of one form of deviationreducing control for the apparatus of FIGS. 1 and 2;

FIG. 5 is an enlarged plan view of one of the controls of FIG. 3;

FIG. 6 is a side view of the control of FIG. 5;

FIG. 7 is a more detailed illustration of an auxiliary unit in the construction of FIG. 3;

FIG. 8 is a detailed illustration of a fuel adjusting assembly typical of the present invention.

FIG. 9 similarly shows a modified adjusting assembly pursuant to the present invention;

FIG. 10 is a partially schematic representation of further modified fuel adjusting apparatus pursuant to the present invention;

FIG. 11 is a circuit diagram of a modification of the apparatus of FIG. 3; and

FIGS. 12, 13, 14 and 15 are views similar to FIG. 10 of modified forms of automatic antiknock adjustment apparatus typical of the present invention.

According to the present invention an automatic apparatus is provided for monitoring and/or adjusting the knock rating of a fuel stream in a fuel supply system which as in a gasoline refinery. For example the invention can take the form of a blending apparatus for automatically producing a stream of blend fuel that has a substantially uniform antiknock rating, said apparatus including a detonation testing engine, a measuring system connected to indicate the intensity of detonation knocking that takes place in the engine and adjusting mechanism connected for automatically adjusting the compression ratio of the engine to keep the detonation intensity at a predetermined value, sampling means connected to receive samples of blend fuel and deliver them to the engine for combustion therein at maximum knock fuel-air ratio, the sampling means being further connected to deliver to the engine samples of a reference fuel for combustion therein at maximum knock fuel-air ratio, the adjusting mechanism being connected to cause the sampling means to automatically shift from one fuel to the other and back again, and automatic control structure connected to the measuring system to control the blending of the stream so as to have the compression ratio of the engine when operated on the blend fuel at a predetermined value based on the compression ratio when operated on the reference fuel.

The sampling means can be connected to automatically shift the engine to the reference fuel whenever the control action exceeds a predetermined limit. The control structure can directly respond to changes in compression ratio or in detonation intensity.

A feature of the present invention is that it can use a test engine and a detonation measuring system, both of which are standard octane rating items, so that the apparatus provides results that closely conform with standard specifications. Best results are also obtained when a temperature control such as cooling means is included in the apparatus to cool the fuel supplied to the engine or compensate for heating of the fuel caused by the apparatus or other sources.

Additionally, one of the problems of automatic gasoline monitoring or blending is the withdrawal of samples of the gasoline and the prompt supplying of these samples to a test engine at a selectable liquid level or height so as to permit the sample to be accurately carburetted into the engine with very little time delay.

According to the present invention the sampling and leveling is readily accomplished with a relatively small container having an overflow type level-determining device or suction tube projecting into the interior of the container from its upper portion for sucking out excess liquid and thereby defining a level for the liquid in the container. g

The suction tube can desirably be threaded through the top of the container and provided with a rotary connection through which it is connected to a suction line while the tube is capable of being rotated and thereby threaded up and down in the container. It is helpful to have a vent opening establishing open communication between the fuel in the container and the outside air if the interior of the container is to be maintained at atmospheric pressure. The vent can be incorporated in the rotary connection as by merely making it a loose fit in the top of the container.

It is also very helpful to have the walls of the container transparent so that the flow of sampling liquid can be readily monitored.

The flow of sampling liquid into the container can be between about 300 and 500 milliliters per minute to provide a liquid at a rate fast enough to rapidly follow the characteristics of the principal stream of liquid being adjusted, without creating so much turbulence in the container as to prevent it from forming an accurate controllable level. To this end the horizontally directed inlet and outlet can be at the very bottom of the container. With this construction the inlet and outlet can be aligned on opposite sides of the container, and if desired a baffle can be interposed to help circulate the incoming liquid through the entire contents of the container before it flows out to the engine.

The apparatus of the present invention is highly suited for automatically monitoring and/or adjusting the octane rating of a fuel stream in a fuel supply sys tem such as in a gasoline refinery. In such an arrangement the automatic knock measuring equipment includes sampling means connected for receiving samples of a fuel stream to be adjusted, and also includes output elements that periodically develop a correction signal corresponding to the difference between the antiknock rating of the sample and a predetermined desired rating. The correction signal can then be used to operate adjusting element such as a mixing valve that controls the amount of high antiknock blending stock to the fuel system, and can adjust the fuel flow in a manner that reduces the magnitude of the correction signal. The high antiknock blending stock can be a refinery stock or it can merely be an antiknock concentrate such as tetraethyl lead with or without scavenger and diluent, or it can be a mixture of refinery stock with antiknock.

For best results the apparatus is arranged to automatically switch the fuel supply to the test engine periodically so that the test engine will operate on a standard or reference fuel sufficiently frequently that any departure in the operation of the engine can be promptly detected and compensated for.

To this end the automatic measuring equipment can have an indicator to show the relative rating of a fuel sample, a standard reference control, means for originally setting the indicator at a predetermined portion of its range, and automatic compensating mechanism connected to periodically cause the measuring equipment to measure the antiknock rating ofa standard fuel and to adjust the indicator so that the rating of the standard fuel corresponds with the standard reference control to compensate for drift of the automatic measuring equipment.

Referring to the drawings, the apparatus of FIG. 1 includes a test engine indicated at which can be of the standard type such as illustrated and described in the 1960 ASTM Manual for Rating Fuels by Motor and Research Methods, published by the American Society for Testing and Materials, Philadelphia, Penna. Such a conventional engine is equipped with an actuator 12 for changing its compression ratio, which actuator is in the form of a reversible electric motor. The apparatus of FIG. 1 is further provided with a second actuator 14 for changing the fuel-to-air ratio of the combustion mixture supplied to the test engine. Actuator 14 can also be electrically operated as by means of a reversible electric motor.

As in the usual test engine construction, a detonation pick-up 16 is provided so as to develop an electrical signal varying in intensity in accordance with the intensity of the detonation or knock that occurs during the operation of the test engine. In the apparatus of FIG. 1 the signals so produced are delivered to an amplifier and deviation computer 18 which amplifies the signals and also determines how far the detonation or knock varies from some predetermined value. If desired the amplified signal can be displayed on a meter such as the usual knockmeter 20. In addition a recorder 22 may be used to make a record of the signals, either indicative of the degree of knock or of the deviation from the predetermined knock intensity, or both. Recorders of this type are well-known and will make records on circular or rectangular charts, usually with a moving pen actuated by the electric signal being recorded as Well as by a timing mechanism that moves the chart.

The automatic testing of the present invention is ef fected by a combination of a deviationreducing control 24, a knock-maximizing control 26 and a sequencer 28. The deviation-reducing control 24 is supplied with signals from the deviation computer 18 and is connected to compression ratio change actuator 12 so as to change the compression ratio in the direction which reduces the difference between a pre-set knock intensity and the knock intensity indicated by the detonation pick-up. The knock-maximizing control 26 is supplied with signals from the amplifier 18 or the detonation pick-up 16, and in turn is connected to the fuelair ratio change actuator 14. Sequencer 28 is connected to operate the two controls 24 and 26 in the appropriate sequence. At the completion of the testing sequence the antiknock rating can be read from an indicator 30 which is conveniently operated by the compression ratio change actuator 12. When operating at the fuel-air ratio for maximum knock intensity, each fuel has one specific compression ratio at which it will produce a standard knock intensity and this compression ratio determines the antiknock rating of that fuel. For ratings up to and including 100, the rating signifies the percentage of iso-octane (2,3,4-trimethylpentane) in a mixture of the iso-octane with normal heptane, which mixture develops the same standard knock intensity under maximum knock conditions at that compression ratio. For fuels having antiknock ratings above 100, the rating similarly represents the compression ratio at which the standard knock intensity is developed under maximum knock conditions by mixtures of iso-octane with tetraethyl lead rather than mixtures of iso-octane with normal heptane.

Indicator 30 can show both the antiknock rating and the corresponding compression ratio, or it can show merely one or the other of these'values. Antiknock ratings have a standard relationship to the final compression ratios, as indicated for example in Table V on page 21 of the above Manual.

For convenience in making preliminary or intervening adjustments of compression ratio, the construction of FIG. 1 can include a manual control 32 such as a simple three-position switch for energizing actuator 12 in one direction or the other, or for setting the actuator so that it is controlled only by the deviation-reducing control 24. A similar manual control 33 can be used for fuel-air ratio changes.

FIG. 2 illustrates the interrelationship between the test engine 10, actuating motor 12 for changing the compression ratio of the engine, and actuating motor 14 for changing the fuel-air ratio. Engine 10 is of the conventional construction with its cylinder 34 movable to and fro along its cylindrical axis. Near the base of the cylinder it is provided with external thread 36 that meshes with internal thread on a rotary nut 38 which is in turn accurately supported so that it does not show any movement in the direction of the cylindrical axis. However, the nut 38 can rotate around that axis and is rotatably driven to and fro in that direction by a worm 40 that meshes with external threads 42 on the nut 38. Worm 40 is in turn driven by the motor 12 as by means of drive coupling 44 and speed reducing gear box 46. Indicator 30 can also be connected to be driven by -worm 40 as by means of the flexible drive shaft 48.

The intake line 50 for enginehasthe usual venturi 52 with a fuel discharge tube 54 leading to and opening in the venturi throat. A fixed fuel level sight glass 56 is shown as in communication with the fuel discharge tube 54 for convenience in reading the height of the fuel level, although such reading is not needed for automatic operation in accordance with the present invention. Flexible conduit 58 connects the fuel discharge tube 54 with a carburetor bowl 60 having a valvecontrolling float 62 that determines the level of the fuel in which the float is immersed. The carburetor bowl 60 is provided with an arm 64 containing a vertical passageway that is internally threadedand threadedly engaged on a vertically disposed externally threaded shaft 66 journaled at its ends in a frame 68. One end of the threaded shaft 66 is connected for rotation by motor 14, and the shaft itself is so supported that it cannot move vertically. Frame 68 is also arranged to guide arm 64 so that the arm carries the carburetor bowl upwardly or downwardly, depending upon which way motor 14 rotates, without permitting the arm to tilt or swing. The higher the float controlled fuel level with respect to the venturi 52, the richer the fuel-air ratio of the mixture delivered to intake line 50.

The usual detonation pick-up 70 is mounted in the head or top of the test engine 10 so that the pick-up has its sensing element exposed to the combustion chamber 72 of the engine. The sensing element can be a simple piezoelectric transducer that generates an electrical signal when subjected to pressure or rate of pressure change, and modulates the signal so that it follows the change pressure or in rate of pressure change. Knocking or detonation during engine operation causes development or pressures higher than for normal combustion and rates of pressure change in excess of those for normal combustion, and the electrical signal corresponding to these high pressures or high rates of pressure change can be readily distinguished. An amplifier 74 similar to that ordinarily used, can be arranged to amplify the electrical signals and make them suitable for reading by knockmeter 20. Amplifier 74 corresponds to the amplifier noted in FIG. 1 as an integral portion of unit 18.

FIG. 3 illustrates an automatic octane rating apparatus of the invention in which a deviation computer and portions of a knock maximizing control are combined in a single unit 90 which can also include the deviation reducing control shown in FIG. 4. Unit 90 is built around a recorder such as the ElectroniK l7 strip chart model available from Minneapolis-Honeywell Regulator Company and described in its instruction manual numbered 367001. The recorder has the usual chart tliat is fed from a supply roll to a take-up roll at a constant speed, and a pen that is traversed across the chart in accordance with variations in electrical signals delivered to an input terminal. These features are well known and since they are not essential parts of the present combination, are not illustrated. The recorder is also equipped with a control slide wire represented at 94 in FIG. 4, that has its wiper or tap 96 moved in accordance with movements of the pen so as to set up a control point having a potential intermediate between that across the ends of this slide wire.

Movement of the pen and tap 96 is effected with the help of pulley 98, and for the purposes of the present invention this pulley is provided with an actuator bar 100 that turns with it and is located so as to close either of a pair of switches 101, 102 when the pulley rotates sufficiently far in either direction. Switch 101 is shown as a low limit switch, and switch 102 as a high limit switch.

Unit is under the control of a sequencer that includes a ganged set of stepping switches 112 driven by a solenoid ratched stepper 114. Six wafer-type switch segments, identified as A, B, C, D, E and F, are in this ganged set along with a set of breaker contacts 116, 118 operated by cam 120. Wafer 112A has a central electrically conductive contact disc 122 rotated by shaft 124 common to all the switch segments, and it has a notch 126 at one portion of its periphery. A wiper or brush contact 128 is fixed and remains in electrical connection with the disc throughout it rotation so as to provide a fixed terminal for electrical connection to that disc. Around the periphery of wafer 112A are seven fixed terminals numbered 1, 2, 3, 4, 5, 6 and 7, each projecting centrally so that they come into wiping engagement with the disc as it rotates. Each terminal is, however, so dimensioned that when notch 126 is brought into opposition to it, the wiping end of the terminal will lie completely within the notch 126 so that terminal becomes disconnected from the disc.

Segments B, C, D, E and F can also be of the wafer type with seven similarly located terminals each, but in each of these a narrow arm 130 is arranged to individually contact one of the terminals at a time as shaft 124 rotates. Arms 130 of each of the segments B, C, D, E, and F are electrically insulated from each other as well as from disc 122, and each has its own fixed wiping contact 140.

Solenoid ratchet 1 14 is connected for energization by a DC source of current such as rectifier which is shown connected through hot lead 151 and grounded lead 152 to a plug 154 that can be inserted in a conventional l 10 volt AC power like receptacle. Fuse 156 and on-off switch 158 can also be included in this circuit.

The sequencer also includes a delay relay generally indicated at 160 for the deviation reducing control and another delay relay for the knock maximizing control. Relay 170- operates in conjunction with an interrupter as well as with delay switches 178 and 179.

Delay relay 160 has three switch armatures 161, 162 and 163 illustrated in the normal position which they take when this relay is not energized. In these positions the armatures engage back contacts. When relay 160 is energized it immediately pulls its armatures over so that they each engage front contacts and this operation is completed without any delay. However, when the relay is deenergized the armatures will be held against their front contacts for a period of about one minute before the armatures are released from their front contacts and permitted to fall back to their back contacts. A dash pot 164 is illustrated as providing the above delay, but any other form of delay mechanism can be used if desired.

Relay 170 is operated in the same manner, a delay dash pot being here represented at 174. A pair of armatures 171, 172 forming part of relay 170 are shown in the normal position they take when this relay is not energized. Winding 173 of relay 170 is energized from either of a pair of parallel leads 184, 186, and in series in lead 184 is the delay switch 179 which is of the normally closed type that stays closed until about twenty seconds or so after power is supplied to lead 184. This type of operation is supplied by means of a heater 188 which forms part of switch 179, in combination with a switch arm 190 of bimetallic nature located so as to be warmed by the heater 188 to the degree required to snap open after the heat has been on for the above period of time.

Switch 178 is of the normally open type, the switch terminals being connected to leads 191, 192, and the heater being separately connected to lead 193.

The sequencer of FIG. 3 also has a reset or start.

switch 200 with two armatures 201, 202 mechanically biased to the illustrated position as by a spring, not shown. In this position armature 201 is out of engagement with a pair of contacts 211, 212, but armature 202 is in engagement with its two contacts 221, 222.

It is also desirable to connect a capacitor 230 across the DC output terminals 231, 232 of rectifier 150, and to connect a resistor 240 and capacitor 242 in series between terminal 232 and solenoid lead 244 with which terminal 232 is intermittently connected by the switching arrangement.

Pulley 98 of unit 90 has, in addition to the low and high limit switches 101, 102, mechanical maximum sensing elements that include a maximum switch 250 with an actuating nose 252 biased outwardly and holding this switch in open position. Maximum switch 250 (FIG. 5) is fixed on a plate 254 which in turn is pivotally secured to a stationary support 256. Mounting screw 258 passes through an aperture in plate 254 and through a bushing 260, and is threadedly engaged in support 256. This mounting screw arrangement permits Terminal l Terminal 2 Terminal 3 Terminal 4 Terminal 5 Terminal 6 Terminal 7 Center contact Terminals l, 2 8L 5 Terminal 3 Terminal 4 Terminal 6 Center contact Center contact Terminals 1 & 5

Terminal 3 Terminal 4 plate 254 to pivot and also frictionally engages the plate sufficiently to keep it from pivoting unless it is rotated by a force of sufficient magnitude. A flat or arched spring friction washer 262 can be inserted between bushing 260 and plate 254 or between the head of the mounting screw 258 and plate 254, to improve the frictional engagement.

Pivoting of the plate is effected by a pin 264 secured to the face of the pulley 98 and arranged to engage the switch 250 as the pulley 98 rotates. A cam lobe 266 in plate 254 cooperates with pin 264 to pull the plate in clockwise direction around its mounting screw as seen in FIG. 5, when the pulley 98 rotates an appreciable distance in counterclockwise direction around its pivot. This clockwise pivoting of plate 254 helps bring switch 250 closer to the pin so that the pin will not have as far to travel when it returns from a counterclockwise excursion. Because the tilting of plate 254 can position switch nose 252 at varying distances from the center of pulley 98, an auxiliary contactor 268 can be used to cover nose 252 and provide engagement for pin 264 regardless of the tilt of plate 254. Auxiliary contactor 268 can be journaled on a pivoted bar 270.

Indicator lights 280 can also be used to show the condition of the apparatus, and a capacitor 282 can be connected between the ungrounded ends of the drive windings for motor 14.

The various leads in the sequencer of FIG. 3 are connected as follows:

terminal 2l2.

terminals 1 and 2 of switch segment C and to first end of high switch back contact for armature 162.

" first end of low switch lead 191.

terminals 5 and 6 of switch segment C.

back contact for armature 163.

" lead 244 (through breaker points ll6,l l8).

terminal 222.

second end of low switch back contact for armature 171.

armature I63.

terminal 21 l and second end of high switch 102.

front contact for armature 162.

winding of relay 160.

carburetor motor (lowering connection).

" lead 184, armature 172,

one terminal of motor of interrupter 180, and one of the interrupter terminals of interrupter of switch segment A to I,

of switch segment B to H of switch segment C to of switch segment D to 1,

Center contacts of switch segments D & E to power supply lead Terminals 2,3,4. 6 & 7

Terminal 4 of switch segment E to of switch segment F to indicator lights carburetor motor Center contact of switch segment F to Second terminal of interrupter 180 to Lead 193 to Armature 162 to FIG. 4 illustrates a highly effective form of deviation reducing control similar to that available commercially as Model I-IP-102 Deviation Proportional Pulse Control Relay of the Minneapolis-Honeywell Regulator Co. As in this commercial model, the control of FIG. 4 has three thyratron tubes 301, 302, and 303 connected with discharge circuits and discharge tripping circuits. Relays 310, 320 and 330 have their windings in series in the respective discharge circuits. Relay 310 has three armatures 311, 312, 313 and simultaneously moves all three to switch-closing position when it is energized by a discharge in thyratron 301. Such discharge is triggered by an adjustable grid circuit 341 and the closing of the grid return circuit through armature 311 shorts out the grid triggering voltage so that the discharge soon terminates.

Meanwhile similar grid triggering circuits 342 and 343 charge up the grids of thyratrons 302 and 303 to their firing voltage, and if the voltage of tap 96 is different from that of tap 340 in a set point slide wire 345, one of these two thyratrons will have its grid voltage raised sufficiently to fire while the other will be lowered a little and will not fire.

Relay 320 is in the discharge circuit of the thyrat on that fires when the voltage of the control slide wire tap is too high, and this relay actuates armatures 321, 322 and 323 from their normal positions, which are illustrated, to their actuated positions in which they close a circuit supplying a pulse of power to decrease lead 351 from a power supply lead 352. At the same time a similar increase signal lead has its open connection further opened to help assure that both increase and decrease signals are not delivered simultaneously.

Conversely, when the relay 330 is energized, it actuates armatures 331, 332 and 333, delivering a pulse of increase signal.

When the potentials of taps 96 and 340 are sufficiently close together, neither the thyratrons 302, 303 fire, and no signal is delivered to line 351 or line 353. In any case, the shunting action of armatures 312, 313 under the actuation of relay 310 resets the firing circuits of thyratrons 302, 303 and prepares them for the next firing trigger.

A feature of the above deviation reducing control is that the correction pulses delivered to line 351 or 353 are longer when the taps 96 and 340 are further apart in potential. As a result the corrections will much more rapidly bring the knock intensity to the standard value as determined by set point tap 340, and will do this with less hunting. I

Typical circuit constants for the circuit of FIG. 4 are given in the drawing (capacitances in microfarads and resistances in ohms) and provide very effective results when used with thyratron plate supplies at 270 AC volts and with grid potential supplies at 29 DC volts measured at their rectifier output capacitors. The potentiometer in the grid circuit of thyratron 301 is preferably adjusted to produce a pulse repetition rate of about one per ten seconds, and the potentiometers in the grid circuits of the other thyratrons adjusted so that thyratrons 302 and 303 just barely miss firing when the control slide wire tap has the same potential as the set point slide wire tap and the thyratron 301 fires. To help follow the operation of the circuit, indicator lights 361, 363 are connected in parallel with output leads 351, 353 and one of these will light whenever a correcting pulse is being delivered. Another light 365 is connected to light when power is supplied to lead 352 and is available to pulsing armatures 321, 322, 331 and 332.

Manual control switches 368, 369 of the momentary contact type are also shown as provided to enable manual pulsing of increase and decrease signals. An automatic disabling switch 370, preferably of the on-off type that remains in the position to which it is moved, can also be inserted in lead 352.

The apparatus of FIG. 4 is interconnected in the combination of FIG. 3 by having the power supply lead 352 of FIG. 3 switched on and off through armature 161 of relay 160 in FIG. 3. In addition another interconnection 354 is used to energize relay 160 whenever a correcting pulse of either kind is delivered by the circuit of FIG. 4.

The assembly of FIG. 3 is placed in operation after connection to the appropriate power supplies, by opeating reset switch 200 to bring the sequencer into position 1 (illustrated), after which this switch is released. When the sequencer is in any other position the action of the reset switch in closing a circuit between contacts 211, 212, completes an actuating circuit from rectifier output terminals 231, 232 to the solenoid 114 through disc 122 of switch segment A and its terminal 1. The solenoid will accordingly rotate the selector one step clockwise as seen in FIG. 3. During this step breaker cam opens breaker points 116, 118 until the step is completed. Holding reset switch 200 down will thus assure the stepping until selector reaches position 1 at which time the notch 126 opens the circuit to terminal 1 of segment A and the actuation is terminated.

At the same time segment D of the sequencer as it reaches position 1 completes a connection from power lead 151 through terminal 1 of the segment to the winding of relay 160. This actuates relay which through its armature 161 starts the correction action of the deviation reducing control of FIG. 4. In the meantime the reset switch 200 is released and this completes a supplementary energizing circuit for the solenoid 114 from disc 122 through terminal 2 of segment A, terminal 1 of segment C, center contact of segment C, actuated armature 162, terminals 221, 222 of the reset switch, terminal 1 of segment B, center contact of segment B, lead 223 and terminal 232. This steps the sequencer to position 2 where the bulk of the correction action of the circuit of FIG. 4 is completed. At this position the notch 126 opens the above supplemental energizing circuit to terminal 2 of segment A so that the sequencer remains in position 2.

During the dwell in position 2 the compression ratio of the engine is brought by the deviation reducer of FIG. 4 to the value that produces a detonation signal corresponding to the predetermined standard as set by set-point tap 340. When the correspondence is sufficiently close, the deviation reducer will not develop a correcting pulse in output lead 351 or 353 and as soon as the time delay of relay 160 runs out, the armatures of that relay return to their deenergized position (the one in which they are shown) and this closes a solenoid actuating circuit from disc 122, terminal 3 of switch segment A, armature 162, terminals 221, 222 of reset switch 200, terminal 2 of switch segment B, center contact of switch segment B, and terminal 232. The solenoid accordingly steps to position 3, where the notch 126 again opens the solenoid circuit.

In position 3 the relay 160 remains deenergized but the switch segment D completes a circuit that energizes the carburetor motor 14 and causes it to lower the carburetor. This lowering leans out the fuel mixture and as a result reduces the knock intensity. As the intensity becomes lower, pulley 98 rotates in counterclockwise direction as seen in FIG. 3, and it will soon bring its arm 100 around far enough to close low switch 101. When this happens another solenoid energizing circuit is established from disc 122 through terminal 4 of switch segment A, low switch 101, terminal 3 of switch segment B, center contact of segment B, and terminal 232. This steps the solenoid to position 4 where notch 126 again stops it.

In position 4 the downward rotation of carburetor motor 14 is stopped, and instead switch segments D and F establish an upward rotating energizing circuit for that motor through lead 151, center contact of segment D, terminal 4 of segment D, lead 184, normally closed delay switch 179, lead 186, center contact of segment F and terminal 4 of segment F. The carburetor motor accordingly now raises the carburetor for a few seconds until delay switch 179 open-circuits. This period is preferably about twenty seconds.

As the carburetor is thus raised, the detonation intensity increases and pulley 98 is rotated clockwise bringing its pin 264 against the nose 252 of switch 250, closing this switch. The closing of switch 250 establishes a carburetor raising circuit as a shunt across delay switch 179. This shunt branches off from lead 184 through the contacts of interrupter 180 and the now closed maximum switch 250, and branches back to the center contact of segment F. Accordingly when delay switch 179 times out, the carburetor continues to rise but now does so in an interrupted manner, as for example moving up in 2 to 5 second steps spaced by 5 to second intervals of no movement. This intermittent upward travel of the carburetor is continued as long as it causes the knock intensity to increase and the pulley 98 to move in clockwise direction. When the maximum knock intensity is reached the pulley no longer rotates, and at the next raising of the carburetor the knock intensity diminishes and the pulley 98 makes a very small return step in counterclockwise direction. This withdraws pin 264 from the maximum switch and promptly permits that switch to return to its normally open position, thus stopping further carburetor movement.

In the meantime delay relay 170 was energized through delay switch 179 when the sequencer first reached position 4, and after delay switch 179 opencircuited, this relay continued to be energized through lead 186 each time the carburetor was driven upwards. Until maximum switch 250 opens, the armatures 171, 172 of the delay relay 170 are accordingly held in actuated position. In this position they prepare a step triggering energizing circuit for the solenoid 114, from terminal 4 of switch segment D to terminal 5 of switch segment A. This energizing circuit is kept open initially by normally open delay switch 178, and after that closes as a result of the heating action through actuated armature 172, actuated armature 171 keeps the circuit open. However, when the maximum switch 250 is opened, the relay 170 is no longer energized and it times out, closing the solenoid energizing circuit. The selector thereupon steps to position 5.

In position 5 switch segment D closes a circuit that I actuates relay 160 and also supplies energy for the deviation reducer to operate and adjust the compression ratio of the engine. The actuation of armature 161 completes the energizing circuit for the deviation reducer, and at the same time actuation of armature 162 closes a stepping circuit for solenoid l 14. This stepping 5 circuit runs from disc 122 through terminal 6 of switch segment A. Terminal 5 of switch segment C, the center contact for switch segment C, armature 162, terminals 221, 222, terminal 5 of switch segment B, the center contact of switch segment B, and terminal 232. The sequencer accordingly promptly steps to position 6, but this does not interfere with the continued operation of the deviation reducer. When relay 160 times out at the end of the new compression ratio search, its arm 163 completes a solenoid stepping circuit that advances the sequencer to position 7. This stepping circuit runs from disc 122 through terminal 7 of switch segment A, armature 163, terminal 6 of switch segment B, the center contact for switch segment B, and terminal 232. In position 7 the measuring cycle is over and the apparatus does not function. It is ready, however, for another measuring cycle which can be initiated by merely operating reset switch 200 for a moment.

The compression ratio developed in step 6.need not be and generally is not the same as the compression ratio reached while the sequencer is in position 2, inasmuch as in position 6 the fuel-air ratio has been brought to maximum knock condition whereas at position 2 no maximum knock fuel-air ratio need have been present. The net result is that in position 6 the compression ratio will be automatically brought to the same value which would be arrived at through the standard A.S.T.M. process for manually measuring antiknock ratings. In fact the automatic process of the present invention can even be considered more accurate in that it eliminates errors that may be inherent in the interpolation which is part of the A.S.T.M. procedure. The maximum knock fuel-air ratio is generally the same when a fuel knocks at standard knock intensity, as when the fuel knocks at other intensities within a significant range above and below standard intensity. It is accordingly unnecessary to go through any more fuel-air adjustment steps after the first.

In some cases, however, the apparatus may be set for one fuel, and then used to test a fuel so greatly different that during the fuel-air adjustment, the operating limits of the apparatus might be exceeded. According to the present invention this is prevented by an automatic recycling arrangement. Thus, if during the lowering of the carburetor the knock intensity increases unduly, indicative of an excessively high initial carburetor position, arm 100 on pulley 98 will be brought into engagement with switch 102 causing that switch to close. This completes a recycle circuit from disc 122 through terminal 2 of switch segment A, high limit switch 102, center contact of switch segment B and terminal 232.

This causes the solenoid 114 to ratchet the sequencer 1' around until notch 126 reaches terminal 2, and in passl sity reaches the same high value during the carburetor raising at sequencer position 4, if this takes place before the maximum knock search is completed. In such Similar recycling also takes place if the knock intene a situation the high limit switch 102 is again closed and the same recycling circuit is completed to return the sequencer to position 2 and another compression ratio search.

The same safety recycling will take place whenever the knock intensity becomes excessive, so long as the sequencer is in any position but position 2. Thus should the sequencer even be in the read-out position (position 7) when a very low octane fuel is added to the carburetor, possible damage from excessive knock will be avoided. It is accordingly not necessary to reset the apparatus when the fuels are changed. No automatic recycling is necessary for position 2 inasmuch as in this position the equipment automatically lowers the compression ratio when the knock intensity is too high, and such lowering takes place quite rapidly when the knock intensity is very high.

In the combination of FIG. 3 the compression ratio change motor 12 is operated from the output leads of the deviation reducer by means of relays 380, 390. The motor itself is shown as operated by a three-phase power supply and each relay has three armatures conventionally arranged to interchange the connections to two leads of the three-phase power supply and thereby provide reversible motor actuation. A set of additional armatures 384, 394 included in each relay is seriesconnected in the energizing circuit for the other relay to thereby reduce the possibility that both relays may inadvertently be operated at the same time. This result is obtained because energizing one relay opens the circuit through which the other must be energized.

Another feature of the present invention is the automatic adjustment of time constant that simplifies and speeds up the use of the apparatus. This is shown more fully in FIG. 7 where a lead 400 from the AC power circuit to compression ratio change motor 12 controls the time constant. This lead is connected through resistor 402 and rectifier 404 to the windings 406 ofa relay 410 and then to the ground return. The windings are bridged by a small capacitance 412 to reduce chatter. Relay 410 has an armature 414 connected to the ground return through the windings 426 of a second relay 430. A back contact 416 for armature 414 is connected to armature 434 of relay 430. A front contact 418 for armature 414 is connected through an adjustable resistor 420 in the output of rectifier 404. A back contact 436 for armature 434 is grounded to the power return and a front contact 438 for this armature is connected through a small resistor 450 to the ungrounded end of windings 426. A second armature 440 of relay 430 is connected to the power lead 400 and has a front contact 442 which returns to ground through windings 456 of a third relay 460. A timing capacitor 452 bridged between contact 416 and its armature 414 arranges for the desired energizatlon of relay 460.

When compression ratio change motor 12 is operated, power is supplied through lead 400 and actuates relay 410. This pulls armature 414 away from shortcircuiting condition with respect to the timing capacitor 452 and permits the timing capacitor to charge up through resistor 420, front contact 418, armature 414, capacitor 452, armature 434 and back contact 436. After about a second or two of charging; the voltage will build up to the point where windings 426 are energized to trip relay 430 and cause its armature 440 to energize the third relay 460. Armature 434 will rapidly discharge capacitor 452. The three relays will then remain in those respective conditions until the power supply to lead 400 is interrupted, when all three relays 410, 430 and 460 will be deenergized.

Relay 460 adjusts the time constant for the knock measurement response by means of two armatures 461, 462 and a resistor 464. In the deenergized condition of relay 460, as illustrated, armatures 461, 462 merely complete the circuits from an amplifier and rectifier combination 470 through a selectable time constant adjusting resistor switching assembly 480 and through a further DC amplifier 490 so that the final signals can be delivered to the deviation computer. The conventional circuits can. be used for units 470, 480 and 490 as in the standard detonation meter, Model 50lA or Model 50l-AP. These meters are made available to the industry from the Waukesha Motor Co., Fuel Research Division, Waukesha, Wisconsin. Waukesha Drawing L-6613-C gives the complete wiring diagram for the above components.

In the construction of FIG. 7, relay armatures 461, 462 are arranged so that when relay 460 is energized these armatures by-pass the resistor assembly 480 and connect unit 470 to unit 490 through a separate resistor 464, which can have a resistance corresponding to the lower resistor of assembly 480. With this arrangement the energization of relay 460 will assure that the detonation time constant will be the smallest available regardless of the setting which selector assembly 480 may have.

It will be evident from the above that when a compression ratio search is being conducted and a correcting signal from the deviation reducer is of such long duration that motor l2 much run for more than one or two seconds, relay 460 is actuated and remains so until the motor stops running. This greatly accelerates the response of the signals supplied to the deviation computer from the knockmeter and is of considerable value in speeding up the automatic measurement as well as reducing hunting. Without the automatic time constant reduction the signals at the deviation computer may still be responding to the latest compression ratio change when the next compression ratio change is called for. For very small compression ratio changes, however, a long time constant can be tolerated and is even preferred since it gives a more stable indication of a final knock intensity.

Although many different circuit constants can be used in the timing arrangement for relay 450, the following have shown very good results.

Resistor 402 1000 ohms;

Resistor 420 minimum 2500 ohms, maximum 5000 ohms;

Capacitor 412 0.25 microfarads;

Capacitor 452 microfarads;

Resistor 450 100 ohms;

Capacitor 427 0.30 microfarads;

Also for the circuit of FIG. 3,

Resistor 240 can be of 10,000 ohms;

Capacitor 242 0.10 microfarads;

Capacitor 282 0.80 microfarads; and

Capacitor 230 0.25 microfarads.

Although control slide wire 94 is shown as part of the combination of FIG. 4, it can be physically located elsewhere and is conveniently a part of unit in FIG. 3. This unit in one practical arrangement is a standard type recorder with a repeater or so-called selfbalancing slide wire as in the above-mentioned Min- 

1. In the process of in-line blending of liquid fuel, the improvement according to which the moving stream of blended fuel has its knock characteristics monitored by continuously operating a knock testing engine on a small sample stream of said fuel and on a reference fuel so as to cause knocking of the engine, automatically switching the supply of said fuels to the engine for such operation so that the engine operates alternately on the respective fuels, continously flowing the sample stream through a level-determining carburetor so that it is carburetted into the engine from a predetermined hydrostatic head, generating from the engine a signal indicative of the relative knock characteristics of the sample fuel, and continuing the flow of the sample stream to the carburetor while the engine is operating on the reference fuel.
 2. The combination of claim 1 in which the flow of reference fuel is stopped while the engine is operating on the sample stream.
 3. The combination of claim 1 in which the fuels are cooled as they move to the engine.
 4. The combination of claim 1 in which the generated signal is used to control the blending.
 5. A fuel monitoring apparatus for in-line blending of liquid fuel, said apparatus comprising a knock testing engine having a carburetor that includes level-determining means, a continuous-flow sample conduit for receiving a sample stream of fuel from the in-line blending and uninterruptedly delivering that stream to the level-determining means, reference supply means connected for delivering to the carburetor a stream of reference fuel, automatic sequencing means connected to the conduit and to the reference supply means to automatically alternate the supply of fuel to the engine between the sample stream and the reference stream, and indicating means connected to the engine to show the knock characteristic of the fuel on which it operates.
 6. The combination of claim 5 in which the level-determining means is a flow-through container into which fuel flows until it reaches a predetermined level and excess fuel flow received subsequently and tending to overflow that level is diverted away from the engine.
 7. The combination of claim 5 in which the carburetor includes a rotating plug valve through which it delivers fuel to the engine from selectable sources. 